The invention relates to a device with a torque-proof first structural component and a second structural component that is connected at least in certain areas in a rotatable manner to the first structural component according to the kind as it is described herein.
In devices known from practice which are embodied with a torque-proof first structural component and a second structural component that is connected at least in certain areas in a rotatable manner to the first structural component, and in which hydraulic fluid can be guided to lubrication points via the first structural component and the second structural component, a pressure drop usually occurs in the area of an interface between the structural components. Such constructional arrangements for transmission of hydraulic fluid between a torque-proof structural component and a second structural component connected therewith in a rotatable manner are for example necessary in planetary gears through which bearing units and tooth meshings are supplied with lubricating and cooling oil to the necessary degree.
Planetary gears are also used in the area of turbo engines, such as aircraft engines. Usually turbo engines have two or three rotors which rotate at different rotational speeds in the same or in different rotational directions. In so-called directly driven machines, a low-pressure turbine or a compressor device of such a turbo engine is directly connected to a fan, whereby the low-pressure turbine and the fan rotate at the same rotational speed. In the next generation of turbofans that have a high bypass ratio, the direct dependency between the fan velocity and the velocity of the low-pressure turbine is eliminated, so that both the fan and the low-pressure turbine can be operated in optimal operational ranges. In this context, an increase of the fan diameter requires a reduction of the fan's rotational speed, whereas the low-pressure turbine's level of operational efficiency can be enhanced by increasing the rotational speed while at the same time reducing the blade radius. The enhanced level of operational efficiency in turn provides the possibility of embodying the low-pressure turbine with a smaller number of turbine stages, whereby the low-pressure turbine is characterized by a lower self-weight and can be manufactured in a more cost-effective manner.
Currently, the coupling between the low-pressure turbine and the fan via a reducing gear in planetary design represents the most efficient method for transmitting the driving power of the low-pressure turbine and for lowering the turbine's rotational speed with respect to the rotational speed necessary for operating the fan. Here, epicyclic reduction gears, either with a planetary carrier that is fixed relative to the housing or with a planetary carrier that is embodied in a rotatable manner, provide the desired reduction ratio as well as high power density.
In the case of a planetary carrier that is fixed relative to the housing, in order to obtain the required reduction ratio in the area of an epicyclic gear or of a planetary wheel set, a compressor shaft of the low-pressure turbine is connected to a sun gear of an epicyclic gear. The hollow wheel is in turn coupled to a fan shaft that is driving the fan. The reaction moments are introduced into the housing in the area of the static planetary carrier. If the hollow wheel is embodied in a torque-proof manner, it comes to a high initial rotational speed in the area of the sun gear and at the same time to a low initial rotational speed of the planetary carrier.
In contrast to this, when it comes to a fan epicyclic reduction gear with a rotating planetary carrier it is provided that hydraulic fluid is transferred under pressure from a static or torque-proof housing structure into a rotating structure or into a rotating planetary carrier for the purpose of supplying lubrication points in the area of the planetary wheel set with hydraulic fluid. Bearing devices and tooth meshings of the planetary wheel set can then be supplied with lubricating and cooling oil to the same degree as the bearing units of an engine's main drive train.
In particular so-called high-velocity planetary wheel sets have to be respectively supplied with a correspondingly large hydraulic fluid volume flow in order to provide a sufficient degree of lubrication and cooling of the tooth meshings and to be able to dissipate the thermal losses that are occurring during operation to an appropriate degree.
The pressure losses that have already been mentioned in the beginning especially occur to an undesirably high level when high oil volume flows have to be transferred between such structural components. In order to limit the pressure losses, the flow cross sections have to be dimensioned so as to be correspondingly large, which, however, leads to an increase in a structural component's weight and installation space requirements.
In commonly used engine concepts, fan reduction gears are supplied with lubrication and cooling oil via an oil supply line that extends through the engine core gas flow. The conduits that carry hydraulic fluid extend through the guide blades of an engine. The larger the oil volume flows that are to be guided to the fan reduction gear, the larger the cross section of the guide blades has to be embodied, as the conduits that are extending through the guide blades and that carry the hydraulic fluid have to be dimensioned with a correspondingly large size. These dependencies in turn require that the air inlet cross-section of an engine be increased, which in turn results in an increase of an engine's weight and in a raised specific fuel consumption, or which has a negative impact on an engine's level of efficiency.